When a virus leaks from a top-secret facility, turning all resident researchers into ravenous zombies and their lab animals into mutated hounds from hell, the government sends in an elite military task force to contain the outbreak.

Kay and Jay reunite to provide our best, last and only line of defense against a sinister seductress who levels the toughest challenge yet to the MIBs untarnished mission statement: protecting the earth from the scum of the universe.